Drill grinding machine



Nov. 2, 1948. w. UMBDENSTOCK DRILL GRINDING MACHINE 4 Sheets-Sheet, 1

Filed Dec. 18, 1944 Nov. 2, 1948.

. Filed Dec. 18, 1944 Y W. UMBDENSTOCK DRILL GRINDING MACHINE I 4 Sheets-Sheet 2 Nov. 2, 1948. w. UMBDENSTOCK DRILL GRINDING MACHINE 4. Sheet-Sheet 5 Filed Dec. 18, 1944 x %\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\&

t mw Nov. 2, 1948. w. UMBDENSTOQK 2,452,702

7 DRILL GRINDING MACHINE Filed Dec. 18, 1944 4 Sheets-Sheet 4 Patented Nov. 2, 1 948 DRILL GRINDING Walter Umbdenstock, Chicag,o-,,1 ll.,, assignor to Lion Manufacturing Cor-11 .1M1011,- Chicago, Ill

a, corporation .of' Illinois Application December 18,1944, serial-1: No, 568mm 9. il a'im The present invention relates; in general to means for and methods of grinding, and has more. particular reference to the produetionof twist drills by grindin suitable drill blanks; the invention further relating to, novel features; in drills produced in accordance with the teachings of, the present invention,

An important object of the invention is to provide for moving a work piece, comprising, a drill blank laterally toward and away from. a grinding element, in timed relationship W th 11 spect to the rotation of the work piece, to: pro..- vide lands along the leading or cutting edges, of the finished drill.

Another important object, is to provide for reciprocating a rotating work piece, longitud nally with respect to a grinding member, and in timed relationship with respect to therotary movement of the work piece, in. order to forxnla finished drill having a ground. shoulderor step therein, which step has a helical configuration; a further object being to provide for, moving the work piece, simultaneously, in a direction laterally toward and away from the grindin element, and, reciprocably, in a direction, transversely of the grinding element and, axially of the work piece' said movements being accomplished: intimed re Another object of the invention is to, provide for'grinding helical surfaces in a work piece while the same is being rotated.

Another object is to provide automatic mechanism adapted to coordinatethe feed of therinding operation to the helix of the lands being ground.

Still another object is to provide a new advancing and retarding mechanism for use in a drill grinding machine, which is adapted, toadvance or retard the rotation of the drill being ground in coordination with the helix of the lands being ground.

A further object of the invention is to provide advance and retard mechanism of the type described above in which the operatingmochanism is centered about two simple and direct acting mating helical gears.

Another object is to utilize a cam for controlling the lateral movement of the work piece toward and away from the grinding element at the cutting edges; making a, finished drill.

Ano her imp rtant. Qbiectis to utilize a. cam for controlling; lon itudinallteciproca .112; more.- mentor the.wcrhpiecewithrespect to-thesrindin-g element; for the purpose. at srindin a. helical step; in the work piece in teamin a t pped drill.

Another important object, is to protlde ain improved: method 0t grindingdrills toif'omn lands along the lateral cutting edges of the drill; by rotating a workpiece-adjacent agri-nd-ing; element and: moving the work piecelaten ally toward and away from the grinding element in timed relationship with respect to the, rotation of the WQIK piece-and inconformitywith the sectional shape 0t the land to=be= formed, whileadvancing or re. tardi-ng such grinding movement in proportion to longitudinal movement of the work piece with ra spect, tothe grinding element, in order conform the lands withthe lateral cutting; edges of the drill.

Another important object is to provide an improved method of grinding drills; havinghelical steps therein by reciprocating; a rotating drill blank or workpiece, in timed relationwith. respectto' the rotation thereof, in grinding relationship with; respect to a; grinding elementand controlling such reciprocating movement so as to form a shoulder, in the drill blank, having a desired helical shape.

Other objects, advantages, and inherent functions' of the invention will become apparent :as th sam is re fully un er to tram. the. .following description, which, taken, inconnection with the accompanying drawings. discloses. aprof rred' mbodimentot the inv ntion.

The accompanying drawings illustrate. a selective embodiment of theinvention in. which.

Fig. 1, is a, planview of, a'drill grinding, ma chine embodying; the invention and showing a laterally and longitudinally reciprocable chuck for presenting. a workpiece to, a grinding wheel in accordance withthe. present invention;

Fig. 2 is a partial sectional view in detail on the line 2-2 of Fig. 1;

Fig. 3 is a partial sectional view in detail on the line 3-3 of Fig. 2;

Fig. 4 is a detail sectional view on the line 4-4 of Fig. 1;

Fig. 5 is a developed circumferential view of cam means for controlling the longitudinal reciprocation of the work piece;

Fig. 6 is a longitudinal view of a drill which the drill grinding machine is adapted to grind, showing the helical shape of the lands and ofthe step shoulder;

Fig. '7 is an end view of the drill;

Fig. 8 is a fragmentary view of a cam for con-. trolling the relative land grinding movement of the work piece and grinding element in a direcdrawings also show a finished drill more particularly in Figs. 6 and '7. It should be understood that a drill may be formed, by grinding, from a '.work piece or blank IUI, comprising a cylindrical rod having a groove or grooves I02 formed therein and defining flutes I03 in the work piece.

grooves and flutes are usually of helical configuration although they may, of course, be straight lateral grooves and flutes in the drill blank. The

leading edge of each flute forms a lateral cutting 'edge I04 of the drill, and the present invention relates to the formation of a raised portion or land I05 in each flute at and adjacent, and behind and extending along the cutting edges of the drill, by undercutting the surface of each flute, as at I06, from the trailing edge of the land I05 to the trailing edge I Iilof the flute.

The invention alsoxcontemplates particularly the relieving or cutting back of the lands to an appreciable extent behind the cutting edges of the. drill, the-lands being relieved uniformly-and progressively from the leading to the trailing edges-thereof, as shown at H38, and, if desired,

the undercut portions of the flutes rearwardlyof the, lands may also be relieved progressively from the trailing edges of the lands to the trailing edges of the flutes, as indicated by the dotted line "39 ,in Fig. 9.

. 1 The invention also contemplates the provision ,of means for'controlling the grinding operation,

.in the formation of stepped drills. A stepped .drill, of course, comprises a drill having a tip portion IIfl of relatively small-diameter and one or more body portions Iltof larger diameter adjacent and behind the tip, the tip and body portlons being interconnected by. a shoulder II2 either. inclined or at right angles with respect to .the axis of the drill and having a cutting edge I I3 joining, the cutting edges N14 or the tip and body portions. The shoulder, also, is preferably joinedlto the body and tip portions bymeans of a curved fillet to avoid formation of burrs in holes cut by the finished drill. It should be understood, iof course, that a stepped drill may have one or 'moreishoulders and two or more drill por- 'tions;-of unlike diameter; The present invention contemplates the grinding or the work piece in such fashion that 'the leading or cutting edge N3 of the step or shoulder is offset forwardly, that is to say, in the direction of the tip of the drill,

The

rality of sturdy columnar legs I5.

4 with respect to the trailing edge l I4 of the shoulder or step, whereby the leading edge of the step may constitute a cutting edge [I3 which interconnects the lateral cutting edges in the drill portions on either side of the shoulder.

The foregoing purposes are accomplished by providing a grinding machine in which a drill blank or work piece may be rotated, in grinding position, preferably at uniform speed. The grinding machine, of course, includes a grinding element, which preferably comprises a grinding wheel and the machine includes mechanism for periodically moving the grinding wheel and Work piece toward and away from each other in a direction laterally, of the work piece, such movement being in timed relationship with respect to the rotation of the work piece so that grinding engagement between work piece and grinding wheel may be accomplished when the flutes I63 of the blank are facing the grinding wheel. The mechanism also is controlled preferably by means of a peripheral cam 58 so that the relative grinding movement, between wheel and work piece, in a direction laterally of the work piece, is in conformity with the desired circumferential shape to be formed in the surfaces of the drill flutes to provide lands at the cutting edges of the drill having the desired relief Hi8 rearwardly of such cutting edges, including undercut flute portions I06 rearwardly of the lands. The mechanism may also be controlled, in grinding a stepped drill, preferably by another cam 49 serving to relatively reciprocate the work piece and grinding element in a direction longitudinally of the work piece, such reciprocating movement being controlled in conformity with the desired helical shape to be imparted in the step or shoulder I I2 to be formed in the drill.

The drill grinding machine herein described includes some of the features contained in a copending application filed by this applicant on October 30, 1943, as Serial No. 508,281, now Patent No. 2,443,194, dated July 13, 1948. However, the machne disclosed herein embodies additional features not found in said copending application.

The drill grinding machine herein disclosed embodies a machine base I8. A suitable grinder head II is supported on the base Iii and a reciprocable carriage or table I2 is mounted for longitudinal movement upon the upper surface of the machine base Id. The table I2 forms a suitable support for a work head it. This work head I3 is adapted to support a work piece or drill blank in grinding position with respect to the grinding element II. The table I2 also supports advancing and retracting mechanism I4 for relatively moving the work piece and grinding element, during the grinding operation, in accordance with the present invention.

Machine base The machine base iii comprises a central box shaped casting I5, which is supported by a plu- The upper surface of the central casting is provided with two slide or guide ways 5's and 38, upon which the reciprocable table I2 may be mounted for longitudinal movement, as shown more particularly in Fig. 3. The-longitudinal way ii is V-shaped so that the reciprocable table I2 may be accurately aligned on the machine base it, whereas the way this flat so that it will not interfere with the aligning function of the V-shapcd way if. The upper portion of the central casting I5 is made in the form of a hollow box so as to reduce the weight of the central casting and still provide sufliclent rigidity for accurate grinding operations. Bear ing-s l9 are preferably cast integrally with the central casting l5 and form a mounting which supports a traverse shaft 28 for free rotation. The traverse shaft 25 maybe rotated by hand wheelZl located in front of the machine and securely fastened to the traverse shaft. Rotation of the hand wheel 2! and the traverse shaft turns a pinion 22 which is securely fastened to the traverse shaft and imparts a longitudinal traverse movement to the reciprocabl-e table H through a rack 23 which is secured to the lower surface of the re-ciprocable table and depends downwardly from the table through a suitable opening in the upper surface of the central casting ill.

The front surface of the central casting l5 also supports a hand wheel 25 which may be associated. with any conventional mechanism to cause transverse movement of the grinder head i l.

Grinder head I'he grinder l i is mounted at the right rear of the Ina-chine base ill and may be of any conventional form provided it supports a grindingwheel 25 for uniform rotation. In addition, the grinder head I i should be provided with means for tilting the axis of rotation of the grinding wheel 25 and securing the same at any desired inclination so that its cutting angle maybe varied in accordance with the work piece being ground.

The reciprocating table The reciprocable table l2 comp-rises a generally flat and heavy metallic slab 26 upon which many of the operating parts of the machine are mounted. The lower surface of the slab 26 is provided with hearing extensions ill and 28. The bearing extension 2'! is constructed in the form of a longitudinally extending rib whereas the bearing extension 28 is formed with a flat bearing surface. The bearing extensions 2'! and 28 mate respectively with the ways l'l' and i8 and provide for guided longitudinal movement of the reciprocable table i2 upon the machine base iii. The rack 23 may be secured rigidly to the lower surface of the metallic slab 25 by any suitable means.

A second metal slab 29 is arranged in substantially parallel overlying relation with respect to the slab 25. The slab 29 is spaced from the slab 26 and the two slabs are secured together at their ear edges by means of a flexible metal'strip 38). This strip 3b is secured to the slabs 25 and 25 by means of a plurality of cap screws 3!. The use of the flexible metal strip as a fastening between the slab-s and 29 imparts a flexible hinge-like mounting whereby the slab 29 may be tilted or rocked vertically with respect to the slab 26.

The work head.

6. relation upon the upper surface ofthe metallic slab 29, and a third bearing block 45. is. 3118051113.- ported: upon the upper suriace of the slab 29 in positionspaced from the bearing blocks 42 and: 43. bearing blocks 43 and 45 rotatably support the'spindle 33;. and all three bearing blocks. d2, 43 i5 rotatably support a drive shaft The gear 46 is secured tothe drive shaft $3. and, accordingly, is rotated by the motor 35 through the gear box 37 and the chain of gears comprising gears 38, 39- and A9. A. helical; gear 4'31 is mounted for rotation with the drive-shaft l6 and. mates with another helical gearil mounted for rotation.- on the spindle 33 so that the chuck 34 may thereby loo-rotated.

Means is provided to axially reciprocate the chuck 35 in timed relation with its rotation. This means comprises a face cam 49 and a cam follower 50. The cam follower 5i? is, preferably, a roller rotatably supported at the end of a thrust transmitting member 5 by means of a shaft 52. The member 51 bears against a thrust bearin 53, which in turn bears against an end of the spindle 33. The spindle 33 is resiliently urged toward the bearing 53 and thrust member 5! by any suitable means, such as springs 54 which are compressed between a collar 55 secured to the spindle 33' and a collar 55 rotatably mounted at the end or the main bearing block 32. The cam surface of the face cam 49 may be formed to correspond to the number of lips of the drill being ground, and to the extent of back-off or clearance desired between the leading and trailing edges of the shoulder or step of the drill being ground.

In Fig. 5. is shown the developed circumferern tial shape of a face cam 49 suitable for use in grinding the helical shoulder H2 in a stepped drill embodying two flutes, the face cam o0mprising two identical portions, one for each flute, and said portions having each a uniformly inclined cam section H5 for thrusting the shaft 33 and consequently the chuck 34 and the work The FTOZ ca J. to a bracket 35 v ich .l to the up er surface of the metal ab 29. The drive from the motor 35 is Power from the spur gear 38 is piece therein progressively toward the grinding wheel as the cam follower 5U rides up such in ciined portion H5, thereby causing the grinding wheel to cut. the shoulder H52 progressively further from the tip of the work piece commencing at the leading edge and progressing toward the trailing edge of the shoulder in one flute. After the flute being ground has passed away from the grinding wheel through the turning of the work piece, the cam follower will ride upon a cam portion- H1 forming a sharp declivity, allowing the spindle or shaft 33 and the chuck 3 carrying the work piece, to move in a direction withdrawing the shoulder H2 from the grinding wheel in an axial direction during the period, the rotation of the work piece, while a groove 552 is opposite the grinding wheel. The work piece is thus retracted to a position in which the grinding wheel may properly grind the leadingedge H 3 of the next flute when the work piece turns intogrinding position, the shape of the shoulder in such flute being determined by the inclination of the second cam portion l- [5.

In addition; means are provided to reciprocate the work piece carried by the chuck 3d transversely in timed relation with the. rotati on of" the work piece so that back-off on clearance may be provided upon the lips of the lands of the drill. This means comprises a peripheral cam 58 itsassocia-ted mechanism. The peripheral cam 58 is secured onthe drive shaft 56' and co-acts with a rotatable cam follower 53, which is rotatably mounted upon the upper end of a crank BIB by means of a pin 6!. The crank Ell is fulcrumed upon a pin 62 and the pin 62 is mounted in a bracket 63 which is secured to the lower surface of a recess in the slab 29 by means of cap screws 34. The lower end of the crank 60 bears against the upper surface of the slab 25 at the point designated generally by the numeral 65 in Fig. 3. As the crank 69 is rocked to and fro through the action of the cam 58 on the cam follower 59, the slab 29 will be raised and lowered with respect to the slab 2t and tilted about an axis comprising the flexible metal strip 3!). The lower end of the crank to is constantly urged in contact with the upper surface of the slab 26 through the weight of the slab 2 and all of the elements carried thereby. The contour of the peripheral cam 53 is selected to correspond with the number of flutes on the work piece and with the shape of the lands and the degree of back-off or clearance desired upon each of the lands.

The fragmentary showing made in Fig. 8 of the drawings illustrates a working section of the cam 58, and it should be understood that the cam will have as many sections as there are flutes in the drill being ground. Since the cam controls the movement of the work piece laterally toward and away from the grinding wheel in order to determine the shape of the flute, the cam 58 comprises a disc having a portion N6 of normal diameter corresponding with the maximum diameter of the drill at its cutting edges I04. Adjacent and connected with this cam portion H6, the cam comprises a uniformly inclined portion I ll, which is designed to move the cam following roller gradually outwardly, thereby tilting the plate 29 and progressively moving the work piece against the grinding Wheel 2% during the grinding of the flute-land I85 including the relieving of the same, as indicated at I08. If no relief of the traifing portions of the land is desired, the cam 58 will have no inclination in its portion I I1 but said portion will have a basic diameter of the portion H6, The portion III, however, merges into a relatively steep shoulder II8 up which the cam following roller 59 will ride at the conclusion of the land grinding stroke to promptly move the work piece and grinding wheel into the relative positions illustrated in Fig. 9 of the drawings, in order to undercut the surface of the flute rearwardly of the land Hi5. After riding the cam section I I8, the cam following roller 59 will ride upon a cam portion I I 9 in order to hold the work piece in position against the grinding wheel to form the undercut drill portion I06. If this undercut portion is to be of uniform depth from the trailing edge of the land I65 to the trailing edge of the flute, the cam portion IIB may be of uniform diameter. If, however, it is desired that the undercut portion of the flute be of progressively increasing depth toward the trailing edge of the flute, as indicated in dotted lines at I09 in Fig. 9, the cam portion H9 may be of progressively increasing diameter, as indicated in dotted lines at I28 in Fig. 8. After the flute being ground has rotated past the grinding wheel so that the wheel is opposite the groove, defining the trailing edge of the flute, the cam follower 59 will ride down a sharply declining cam portion I2I joining the end of the cam portion I19 with a following cam portion of uniform diameter IIB so as to retract the work piece from the grinding wheel, while the same is opposite a groove, into position to repeat the grinding cycle on the next succeeding groove presented to the grinding wheel.

The face cam 49 and the peripheral cam 58 are each independently secured to the shaft 46 by means of set screws or the like, not shown, so that both the axial reciprocation and the transverse reciprocation of the work piece may be adjusted to suit the particular work piece being ground. Since the cams are driven directly from the same source of power as that which rotates the work piece, the reciprocation of the work piece is in synchronism with its rotation.

Advancing and retarding mechanism The majority of the work pieces upon which a grinding machine of the disclosed type is used are provided with helical rather than straight flutes. Accordingly, means is provided for advancing or retarding the rotation of the work piece with respect to its transverse reciprocation, the advancement or retardation being proportional to the longitudinal feeding movement of the work piece with respect to the grinding wheel. This advancing and retarding action is accomplished by shifting the helical gear 41 longitudinally upon its drive shaft 46, in accordance with the feeding movement of the carriage I2. Any suitable means may be provided to permit the longitudinal shifting of the helical gear 41. As shown, a long key 66 is imbedded in the drive shaft 48 and mates with a suitable slot in the bore of the helical gear 47. Naturally comparable means, such as a spline or the like, may be substituted.

As the helical gear 47 is shifted longitudinally in one direction, the rotation of the chuck 34 will be advanced with respect to its reciprocation, and

I shape of the land being ground. A collar 61 embraces the ends of the gear 41 and is slidably mounted in the upper plate 63 of the advancing and retarding mechanism I4. The upper plate 68 is secured to the bearing blocks 43 and 45 and is provided with tongued ways which co-act with mating grooves in the collar 61, as at 69, in Fig. 4.

The collar 61 is longitudinally shifted through the action of a lever arm in. The collar 61 is connected to the upper end of the lever arm ID through the medium of a connecting link I I. The lever arm I'll is provided with a shiftable fulcrum I2 which may be set in any preselected position to give any desired length of lever arm. This fulcrum comprises a shiftable dog I3, which is vertically slidable on a way I4. The way 14 forms an integral part of the lever arm I0 and the dog I3 is secured at any desired position by means of set screws 15. The dog I3 is provided with a nut and bolt I6, the bolt of which fits into a slot along the lower edge of a link ll. This link TI is pivotally mounted, as at I8, to a way I9 which is integral with an L-shaped arm 80. The arm is secured to the casting I5 of the base II] by means of brackets 8i and 82. The arm is slidable in the brackets so as to permit a longitudinal adjustment of the fulcrum I2 and it may be secured in any shiftable position through the tightening of a set screw 83. The right hand bracket 82 loosely embraces the L-shaped arm so as to permit an easy shifting when the set screw 83 is loosened. The arm 30 is also provided with a brace 84 so that rigidity is insured.

The lever arm I0 is shifted about its fulcrum I2 through the medium of a crank 85. The crank 85 is located at the right end of a shaft 86 and this the reoiprocable table I2;

95 shaft 86 is journaled in a bearing 81, which is secured to the right end of the metal slab 26 of The left end of' the shaft 86 is screw-threaded and mates with a nut 88, which is fastened to the lever arm 10, as at 89. As the crank 85 is turned in one direction,

the nut 58 will be fed upon the threaded end" of the shaft 85 and will cause the lever 10 to move the collar 6'5 to the right.- If the crank. 85 is rotated in the opposite direction, then therevers'e occurs. The longitudinal shifting. of the collar 61 is synchronized with the longitudinal movement of the table l2. This synchronism is accomplished by having boththe table and the fulcrum shifted by the same lever arm. A triangular shaped bracket all is secured by means of screws 9| to a' way 92 on the front face of the slab 26. The bracket Sii may be shifted longitudinally and is maintained at its shifted position by means of the screws SI. The lever arm i is pivotally mounted upon the lower end of the bracket 90, as at 93.

Any desired synchronism between the longitudinal shifting of the table l2 and the advancing or retardation of the spindle rotation may be accomplished by varying the position of the fulcrum 52. As the fulcrum 12 is moved toward the pivot 93, the rate of retardation or advancement of the rotation of the spindle with respect to the longitudinal movement of the table will increase, and as the fulcrum I2 is moved about the pivot 93, as for instance to the dotted line position in Fig. 1, a reversal in advancement or retardation with respect to the table movement will take place.

- inc m s, l t vey fix with pect to said;

tiveto the grinding means I in synchronismgwith the. drill rotation for relief grinding. In a d i g nd ma i alonsitu inallir; movable. table, means to move said tablebgr nlir table, drill carrying means mounted'sa table, means to rotate said drill carryingmeans; including as members: a driving helical =pinion and a, meshing driven helical gear, an angularly;

-movable armoperatively attached to one-of-saiid:

longitudinal movement ofsaid table will actuate;

The use of the shiftable fulcrum 12 and the provision for so shifting it that the advancement or retardation of the spindle may be reversed with respect to the table movement, enables this machine to be used upon both right and left hand drills and upon lips of any helix.

Changes may be made in the form, construction and arrangement of the parts without departing from the spirit of the invent-ion, and the right is hereby reserved to make all such changes as fairly fall within the scope of the following claims.

The invention is hereby claimed as follows:

i. In a drill grinding machine, means for rotating the drill, grinding means, means to move the drill longitudinally relative to the grinding means, said drill rotating means including a driven gear and a driving pinion, and means to sh ft said pinion relative to said gear to vary the timed driving relation therebetween during longitudinal movement of said drill.

2. In a drill grinding machine, means for rotating the drill, grinding means, means to move the drill longitudinally relative to the grinding means, said drill rotating means in eludi g driven helical gear and a helical driving pinion, and means to shift said pinion relative to said gear to vary the timed driving relation therebe ween during longitudinal movement of said drill.

3. In a drill grinding machine, means for rotating the drill, grinding means, means to move the drill longitudinally relative to the grinding means, said drill rotating means in-- cluding a driven helical gear and a helical driving pinion, means to shift said pinion relative to said gear to vary the timed driving relation therebetween during longitudinal movement of said drill, and means to oscillate the drill relasaid armto shift one-o sai membe srel'ativetch ther. I

5. In a drill grinding machine, a longitudinally mevable table, means to move saidtable, grind;- ing means relatively fixed with respect: togsaid table, drill carrying, means mounted upon said table, means to rotate said drill carrying means including as members a driving helical pinion and a meshing driven helical gear, an angularly movable arm operatively attached to one of said members, a fulcrum for said arm, means pivotally attaching said arm to said table whereby longitudinal movement of said table will actuate said arm to shift one of said members relative to the other, said fulcrum being adjustable to vary the amplitude of movement of said arm under actuation of said table.

6. In a drill grinding machine a longitudinally movable table, means to move said table, grinding means relatively fixed with respect to said table, drill carrying means mounted upon said table, means to rotate said drill carrying means including as members, a driving helical pinion and a meshing driven helical gear, an angularly movable arm operatively attached to one of said members, a fulcrum for said arm, means pivotally attaching said arm to said table whereby longitudinal movement of said table will actuate said arm to shift one of said members relative to the other, and means manually to adjust the relative position of said members.

7. In a drill grinding machine a longitudinally movable table, means to move said table, grinding means relatively fixed with respect to said table, drill carrying means mounted upon said table, means to rotate said drill carrying means including as members a driving helical pinion and a meshing driven helical gear, an angularly movable arm operatively attached to one of said members, a fulcrum for said arm, means pivotally attaching said arm to said table whereby longitudinal movement of said table will actuate said arm to shift one of said members relative to the other, means manually to adjust the relative position of said members, said last named means comprising a nut pivotally attached to said arm and an operating rod engaging said nut.

8. In a drill grinding machine a longitudinally movable table, means to move said table, grinding means relatively fixed with respect to said table, drill carrying means mounted upon said table, means to rotate said drill carrying means including as members a driving helical pinion and a meshing driven helical gear, an angularly 9. In a drill grinding machine .a longitudinally movable table, means to move said table, grinding means relatively fixed with respect to said table, drill carrying means mounted upon said table, means toi rotate said drill carrying means including as m bers a driving helical pinion and a meshing: ven helical gear, an angularly movable arm operatively attached to one of said members, a fulcrum for said arm, means pivotally attaching d arm to said table whereby longitudinal m ment of said table will actuate said arm to s cm of said members relative to the other, we s manually to adjust the relative position ofsaid members, said last named means comprising a nut pivotally attached to said arm and an operating rod engaging said nut, said fixed member being adjustable relative to said arm.

WALTER UMBDENSTOCK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 286,663 W'heeler Oct. 16, 1883 805,170 Thomas Nov 21, 1905 1,323,452 Cogsdill Dec. 2, 1919 1,640,994 Hanson Aug. 30, 1927 2,099,721 Cogsdill Nov. 23, 1937 2,192,370 Wildhaber Mar. 5, 1940 2,193,186 Bannister Mar. 12, 1948 FOREIGN PATENTS Number Country Date 559,483 Great Britain Feb. 22, 1944 

